Researchers pinpoint start of nausea, vomiting in pregnancy

Most pregnant women develop nausea and vomiting within a certain time period after ovulation, according to research published in BMC Pregnancy and Childbirth.

“The precise course of pregnancy sickness is unknown, but this research shows that it occurs at a specific developmental stage, in a specific timeslot,” Roger Gadsby, BSc, lead author of the study and honorary associate clinical professor at the University of Warwick, United Kingdom, said in a press release.

Gadsby and colleagues conducted a prospective cohort study of women who were trying to become pregnant and presented for care from May 12, 2014, through November 25, 2016.

The participants provided a history on previous pregnancies, menstrual cycle information and demographic information. At day 1 of their first menstrual cycle after recruitment, women collected urine samples each morning and completed daily diaries on nausea and vomiting.

The researchers assessed urine samples for a surge in luteinizing hormone — which precedes ovulation by about 1 day — and for human chorionic gonadotropin to identify pregnancy and early pregnancy loss.

A total of 256 women who achieved pregnancy in a 1-month period completed daily diaries on nausea and vomiting.

Among them, 94.1% experienced symptoms of nausea and vomiting during pregnancy, with 35% of women reporting that they just experienced nausea and 59% reporting that they experienced both nausea and vomiting.

Gadsby and colleagues determined that 88% of women had a rise in human chorionic gonadotropin within 8 to 10 days of ovulation, compared with 20 days to 30 days from last menstrual period.

According to the researchers, this finding suggests that the day of ovulation is a more precise measure of pregnancy.

Gadsby and colleagues also found that two-thirds of women had nausea or vomiting symptom onset within 11 to 20 days of ovulation. In comparison, 67% of women experienced symptoms from 26 days to 40 days after their last menstrual period.

They determined that the median days from ovulation to nausea and vomiting symptom onset was 16 days from ovulation, and 32 days from last menstrual period.

“In the past, women suffering with nausea and vomiting in pregnancy have had their symptoms trivialized and overlooked because it was thought there was a psychological basis for the symptoms,” Gadsby said. “This research further reinforces that nothing could be further from the truth, that this is a biological problem related to the development of the early fetus.”